The densification behavior and the microwave dielectric properties of RBS-(MgCa)TiO3 (R: MgO, CaO, SrO or BaO, B: B2O3 and S: SiO2) glass-ceramic composite materials were systemically examined. The BaBS glass materials possess highest dielectric constant (K) and quality factor (Q) among the RBS glass materials and the BaBS-(Mg,Ca)TiO3 composites materials also exhibited largest K- and Q-value among the RBS-(Mg,Ca)TiO3 glass-ceramic composite materials. Comparison on the measured K-(Q-) values from the calculated K-(Q-) composition lines implies that the formation of additional crystalline phase other than (Mg,Ca)TiO3 materials markedly modifies the Q-value, but is insignificantly altering the K-value for the composite materials. (C) 2002 Elsevier Science B.V. All rights reserved.